EP0225549B1 - Electrically conductive brick - Google Patents
Electrically conductive brick Download PDFInfo
- Publication number
- EP0225549B1 EP0225549B1 EP86116469A EP86116469A EP0225549B1 EP 0225549 B1 EP0225549 B1 EP 0225549B1 EP 86116469 A EP86116469 A EP 86116469A EP 86116469 A EP86116469 A EP 86116469A EP 0225549 B1 EP0225549 B1 EP 0225549B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- holes
- brick
- bricks
- electrically conductive
- flakes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B7/00—Heating by electric discharge
- H05B7/02—Details
- H05B7/06—Electrodes
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Vertical, Hearth, Or Arc Furnaces (AREA)
- Conductive Materials (AREA)
- Compositions Of Oxide Ceramics (AREA)
Description
- The invention relates to an electrically conductive brick according to the precharacterising part of
claim 1. - In d.c. arc furnaces there are often used electrically conductive bricks which are included in the hearth connection (bottom electrode). These bricks often contain an oxidic material intermixed with graphite flakes. The oxidic material may consist of magnesium or aluminium oxides or oxides of silicon or zirconium. One problem in connection with such bricks is how to provide sufficient heat insulation while at the same time maintaining a good electrical conductivity. For these reasons it has been necessary to make the bottom thicker than otherwise would be necessary. Directional electric conductors in the form of graphite flakes constitute at the same time directional thermal conductors.
- Similar problems exist for other arc furnaces in which conductive bricks are required, or for ladle furnaces, for example d.c. ladle furnaces.
- The invention aims at the design of an electrically conductive brick which exhibits a relatively high heat insulation and a good electrical conductivity at the same time.
- To achieve this aim the invention suggests an electrically conductive brick according to the introductory part of
Claim 1, which is characterized by the features of the characterizing part ofClaim 1. - Further developments of the invention are characterized by the features of the additional claims.
- By pressing the bricks, a certain direction of flakes is obtained (in the vertical direction in the Figure when pressing occurs in a horizontal direction). The holes in the brick provide good heat insulation without preventing the current flow to any significant degree. Though for reasons of strength, the holes are not made to be through holes, they provide good heat insulation against the heat from the furnace to its outer side, i.e. the bottom in the Figure. This can also be expressed such that in the manufacture of electrically conductive bricks, a directional porosity is arranged, by a special embodiment of the press mould, perpendicular to the direction to which the graphite or other conductive flakes conform during the pressing operation. In this way, a lower thermal conductivity is obtained without significantly reducing the electrical conductivity.
- Increasing the porosity results in improved heat insulating capacity. By directing the porosity in this way, thus obtaining hollow bricks of the type used in the building industry, the insulating capacity is increased. However, a layer structure must be achieved in which, for electrical reasons, the layers must be interconnected. Therefore, the holes should be made horizontally flat and oriented in the furnace bottom so that their longitudinal extension becomes perpendicular to the direction of the flakes. As already mentioned, for reasons of strength as well as moulding technique, the holes should not be through-holes. The greatest compressive stresses are expansion forces in the lateral direction and not the ferro-static pressure. Non-continuous holes and a small total hollow sectional surface should be dimensioned such that the bricks are capable of with-standing lateral pressure.
- The convection in the holes is small because of a small temperature difference. The surfaces of the holes may possibly be coated with colour or a ceramic surface layer which has a low emission coefficient to reduce thermal radiation from one hole wall to the opposite hole wall. The holes are oriented such that the intrusion of melt can occur only parallel to the boundary between the bottom lining and the melt.
- The bricks according to the invention are exemplified in greater detail in the accompanying drawing. The single Figure of the drawing shows an embodiment of a brick according to the invention which forms part of a hearth connection or bottom electrode of a d.c. furnace, in which a certain layer consists of bricks which are electrically conducting according to the Figure. The electric current is conducted from the
melt 1 to the side of the hearth connection 2 vertically through the brick. As can be seen from the Figure, thegraphite flakes 3 are oriented in a direction from themelt 1 to the hearth connection 2. The current will flow in the same direction as indicated by arrow 4. Theholes 5 are arranged partially across the direction of the current (4) and have an oblong cross-section, for example oval, the broad sides being disposed perpendicular to the direction of the flakes and the current. The three upper holes in the brick are shown in dashed lines. However, the other holes are of a similar kind, and as shown in the Figure, the holes are disposed in a staggered relation forming a zigzag path for the current on its way between these holes along the flakes to the cold side, that is, to the hearth connection 2. The direction of flakes is obtained by the flakes being oriented perpendicular to the pressing directions during the pressing operation. The holes are disposed perpendicular to this direction of flakes. As shown in the Figure, the holes extend at least through half of the horizontal width of the brick; however, other lengths - both shorter and longer - may also exist. - The bricks can be arranged in the hearth connection in d.c. arc furnaces, or in the bottom or in the wall of an arc furnace in which electric bricks are required, or in d.c. ladle furnaces. The mass adjacent the conductive grains may be composed of normal oxide material such as magnesium or aluminium oxides, or silicon, zirconium or other oxides.
- The graphite flakes can be replaced by or supplemented with metal shavings which may also be of an electrically conductive kind.
- The means according to the above can be varied in many ways within the scope of the following claims.
Claims (3)
- Electrically conductive brick containing flakes of graphite or other electrically conductive material in flake form (3), the brick being pressed into final shape, with a number of holes (5) being arranged in the brick, which holes do not pass entirely through the brick, characterized in that the holes extend with their longitudinal direction substantially perpendicular to the predominant direction of orientation of the flakes (3).
- Brick according to claim 1, characterized in that the cross-section of the holes (5) is non-round, for example oval, with their wider sides substantially perpendicular to the direction of said flakes.
- Bricks according to claim 1 or 2, characterized in that the bricks are arranged to be included in the bottom and/or the wall of an arc furnace, in which electrically conductive bricks are required, or in the bottom of a d.c. arc furnace, possibly a ladle furnace, where the bricks are included in the hearth connection or the bottom electrode portion.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE8505659A SE456853B (en) | 1985-12-02 | 1985-12-02 | ELECTRIC CONTROLLING TILE AND USE THEREOF |
SE8505659 | 1985-12-02 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0225549A2 EP0225549A2 (en) | 1987-06-16 |
EP0225549A3 EP0225549A3 (en) | 1988-06-08 |
EP0225549B1 true EP0225549B1 (en) | 1993-07-14 |
Family
ID=20362300
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86116469A Expired - Lifetime EP0225549B1 (en) | 1985-12-02 | 1986-11-27 | Electrically conductive brick |
Country Status (6)
Country | Link |
---|---|
US (1) | US4701931A (en) |
EP (1) | EP0225549B1 (en) |
JP (1) | JPH0717433B2 (en) |
DE (1) | DE3688699T2 (en) |
SE (1) | SE456853B (en) |
ZA (1) | ZA868999B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4221101C2 (en) * | 1992-06-26 | 1994-05-05 | Veitsch Radex Ag | Use of a refractory ceramic mass for lining floors on electric arc furnaces |
GB2393500B (en) * | 2003-01-29 | 2004-09-08 | Morgan Crucible Co | Induction furnaces and components |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US122908A (en) * | 1872-01-23 | Improvement in fire-bricks and stove-linings | ||
US1775396A (en) * | 1928-05-31 | 1930-09-09 | Vesuvius Crucible Co | Refractory brick |
US2154414A (en) * | 1938-03-05 | 1939-04-11 | Teeters Thomas | Furnace construction |
US4101725A (en) * | 1976-08-16 | 1978-07-18 | Nikolai Semenovich Shelepov | Hearth electrode for melting furnaces |
SE445584B (en) * | 1981-05-25 | 1986-06-30 | Asea Ab | LIGHT BAG OVEN INFO |
SE436819B (en) * | 1983-06-01 | 1985-01-21 | Asea Ab | DC LIGHT REVERSE WITH AT LEAST ONE CATODICALLY CONNECTED ELECTROD AND AT LEAST ONE BOTTLE CONTACT |
SE449132B (en) * | 1984-01-25 | 1987-04-06 | Asea Ab | DC LIGHT REAR OR PUMP FOR HEATING |
-
1985
- 1985-12-02 SE SE8505659A patent/SE456853B/en unknown
-
1986
- 1986-11-27 EP EP86116469A patent/EP0225549B1/en not_active Expired - Lifetime
- 1986-11-27 DE DE86116469T patent/DE3688699T2/en not_active Expired - Fee Related
- 1986-11-28 ZA ZA868999A patent/ZA868999B/en unknown
- 1986-11-28 JP JP61284107A patent/JPH0717433B2/en not_active Expired - Lifetime
- 1986-12-02 US US06/936,810 patent/US4701931A/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
SE456853B (en) | 1988-11-07 |
SE8505659D0 (en) | 1985-12-02 |
US4701931A (en) | 1987-10-20 |
DE3688699D1 (en) | 1993-08-19 |
SE8505659L (en) | 1987-06-03 |
EP0225549A3 (en) | 1988-06-08 |
JPS62143862A (en) | 1987-06-27 |
ZA868999B (en) | 1987-06-24 |
EP0225549A2 (en) | 1987-06-16 |
JPH0717433B2 (en) | 1995-03-01 |
DE3688699T2 (en) | 1994-02-17 |
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